Cyclocondensation reaction of 1,2‐diamino‐4‐methylbenzene and <i>p</i>‐substituted acetophenones

Abstract

Abstract 1,2‐Diamino‐4‐methylbenzene 1 reacts in the presence of sulphuric acid with 4‐substituted acetophenones 2a‐e yielding 2,4‐diaryl‐2,3‐dihydro‐2,8‐dimethyl‐1 H ‐1,5‐benzodiazepines 3a‐e and as minor component 2,4‐diaryl‐2,3‐dihydro‐2,7‐dimethyl‐1 H ‐1,5‐benzodiazepines 4a‐e . The ratio 3:4 is in the range of 7:3. The structure determination of the regioisomers was performed by NOE measurements.